1. Technical Field
This invention relates to measurement systems for measuring the topology of surfaces of variously shaped work pieces, and more particularly to a surface finish measuring device for measuring the topography of involute surfaces such as gear teeth.
2. Discussion
Surface measuring devices are used in a wide variety of applications to measure the topologies of the surfaces of variously shaped work pieces. Such measurement systems have utility in performing topological analysis of gears and gear teeth having involute-curved surfaces. Topological analysis of gear teeth surfaces is important in determining the cause of and alleviating gear noise, vibration, etc.
One drawback that has existed with heretofore available measurement systems is the inability of such systems to provide uniformly spaced measurement points when measuring involute gear teeth surfaces. With involute surfaces, the velocity at which a probe or other measuring device traces the surface will vary as the probe moves from the edge of the root to the outermost edge of a gear tooth while the gear is being rotated at a constant angular velocity. As a result of this change in velocity of the probe, measurement samples which the probe obtains at uniform, fixed time intervals over various points on the involute surface of the tooth will vary in spacing. Put differently, the distance between consecutively measured points on the involute surface will vary rather than remain constant as the probe traces the involute surface.
The above described change in distance between the points measured by the probe causes a strip chart recorder, plotter or other like graphic display instrument displaying a graphical representation of the measured points to generate a non-uniform graphical representation of the involute surface. This non-uniform graphical display hinders the efficacy of graphical displays in providing accurate graphical representations of the topographies of involute surfaces.